Phased arrays are used in communications, arbitrary field manipulation, ranging, and sensing applications like radar. A phased array system capable of beamforming using only electronic components—and without any mechanical parts—has an enhanced flexibility and robustness, a relatively higher resolution scan, faster scanning rate, and an improved overall performance.
A phased array includes an array of antenna elements each with an independent phase controller. By tuning these phases, an array can utilize the coherent addition and subtraction of propagating waves to shape the reception or transmission pattern. A phased array transmitter often drives its antennas with the same signal and different phases to generate a steerable propagating beam. A phased array receiver adds the signals it receives from its elements in order to increase sensitivity to a certain direction while attenuating signals received from other directions. Such beamforming allows for wireless transmission and reception along a given direction without the need to physically move a large antenna.
Systems such as radars and telecommunication equipment need to rapidly transmit and receive data. Such systems may use two antennas, one for transmission and one for reception. Alternatively, such systems can use one antenna to receive and transmit data but at different times. Systems that use one antenna for signal transmission and another antenna for signal reception occupy twice the amount of space or have half the bandwidth of system using a single antenna. Therefore, it is highly desirable to have a full duplex system capable of transmitting and receiving data continuously with the same antenna. Such a system would require a high degree of isolation between its transmitter and receiver units.
In order to achieve full transmission from the transmitter to antenna and antenna to receiver, conventional systems require multiple components such as magnetic elements, active circuits, or time-varying circuits. Such elements are relatively large and expensive. A need continues to exist for a full duplex phased array that used a single non-reciprocal element to drive its antennas.